Topic 2 - Principles of infectious disease

Outcomes

get sick and die

get sick and get better

do not get better

Got sick and die

weaker immune system

higher pathogen load

comorbidity

Comorbidity

pre-existing condition

Got sick and recovered

better functioning immune system

lower pathogen load exposure

prior exposure to similar strain via illness or vaccine

Did not get sick

was immune

exposure was below threshold for pathogen success

genetically resistant

Population densities

areas with high numbers of people close together can see faster transmission of airborne and touch-based illnesses

Endemic disease

always present somewhere

populations grow → new susceptibles

results in populations that are more resistant to infectious agents as a whole

Transmission of infectious agents

Airborne

Fluid-to-fluid contact

Insect or animal vectors

Water or food

Healthcare associated infections

Airborne

most efficient

highly contagious

dust particles

require harsh vaccination campaigns

covid, influenza, smallpox, TB, measles, whooping cough

Fluid-to-fluid contact

sexually

open wound contact with infected fluid

HIV, syphilis, gonorrhea, Ebola, HPV, Marburg, chlamydia

Insect or animal vectors

mosquitos → dominant source of infectious agents

ticks, flies

bites

malaria, yellow fever, zika, West Nile, Lyme disease, rabies, bubonic plague

Water or food

usually associated with oral-fecal route

ingestion results in illness

cholera, typhoid, poli, E. coli, salmonella

Healthcare associated infectious (HAI)

unhygienic practices

unvaccinated workers

MRSA, any infection

Reducing transmission of infectious diseases

vaccination

education

voluntary isolation

sanitary practices

insect control

rodent control

observations post worldwide